Interlocking Rocking CLT Shear Walls with Viscous Dampers

摘要

While the use of cross laminated timber (CLT) has become more common, the implementation of CLT as shear walls remains rare because there is no universally recognized response modification coefficient, R, currently adopted for base shear. In addition, CLT shear walls are relatively stiff as a seismic force resisting system and inelastic behavior of the system is often relegated to vulnerable connections. There is also an inherent issue with instability due to overturning in multi-story buildings due to transportation limitations on the size of CLT panels. Past research by others has successfully utilized post-tensioning to create self-centering rocking CLT shear walls which decrease the stiffness of the system and address issues of instability, however, sliding resistance at the base becomes a unique challenge. The use of damping systems to increase the ductility of the system while limiting drifts has also been investigated successfully. These systems generally utilize U-shaped flexural plates or slip-friction plates as a method of energy dissipation, both of which require custom design and custom modeling techniques. This study uses a numerical dynamic analysis to investigate a novel system of self-centering, interlocking rocking CLT shear walls integrated with paired viscous dampers. These damping devices are implemented between aligned rocking walls to reduce the spectral response and drifts during a seismic event, and to eliminate residual drifts and therefore the need to replace components after a seismic event. Additionally, the interlocking aspect allows for dampers to be hidden out of sight within the cavity between floor levels, and the use of commercial fluid viscous dampers allow for ease of analysis for the practitioner. This study substantiates that the proposed system has enough stiffness and energy dissipation capabilities to limit roof displacements while exhibiting a reduced seismic response, and proposes design solutions to resolve sliding at the base. The result is reduced base shears and improved ductility of the seismic force resisting system that could potentially justify higher R values than that currently published.